Linaro has built a 64-bit version of Android 4.4 for developers to write and test applications for ARM-based mobile devices

Google is being tight-lipped about when the 64-bit version of Android will be released, but Linux development group Linaro has built a version of the open-source operating system so mobile applications can be written and tested by manufacturers and developers rushing to catch up with Apple.

Android smartphones and tablets could be faster with 64-bit hardware and also carry more memory. Device makers are feeling pressure to catch up with Apple, which jumped ahead of the competition by putting its 64-bit A7 processor in the iPhone 5S and iPad Air. Linaro's Android builds are not full-fledged distributions of the OS, but are system builds meant for developers to write and test applications.

The Linaro development group has tested a version of the 64-bit OS -- based on the 32-bit Android 4.4, code-named KitKat -- on actual 64-bit ARM chipsets, which are not yet available in Android smartphones and tablets. However, since Linaro's 64-bit developers version of Android offers backward compatibility, third-party developers can run the OS on existing 32-bit tablets like Google's Nexus 7 and 10, and an emulator can be used to test 64-bit applications.

The final release of 64-bit Android will depend on Google, which will take the available open-source code and make tweaks before releasing the OS. Adoption of 64-bit Android on mobile devices will be swift if software, drivers and tools are ready ahead of the OS release, Linaro CEO George Grey said.

"It seems to me a lot of companies are looking to push phones based on [64-bit] later this year," Grey said.

Industry observers believe Google could announce a 64-bit version of Android at the Google I/O conference in late June. Qualcomm, Nvidia, Marvell and MediaTek have announced 64-bit mobile chips, but have declined to talk in detail about the work they are doing to bring the 64-bit version of the OS to those chipsets.

Linaro's focus is on building Linux-based software, tools and drivers for ARM's 64-bit ARMv8 architecture. The organization initially focused on servers, but mobile devices became a priority with more ARM-based chip makers announcing 64-bit processors.

Linaro has 200 engineers and is bankrolled by member organizations, which has helped speed up contributions, Grey said. Linaro has also made contributions to the Chromium browser for 64-bit Android, and also to the QEMU system model, a hardware emulator to replicate a virtualized OS environment.

Linaro is providing monthly engineering Android builds based on the 64-bit kernel for developers to download. The group has been working on code that Google and other open-source developers have been putting into the AOSP (Android Open Source Project) repository. The engineering images are based on the latest Linux 3.14 kernel. A stable image is provided every three months.

"AOSP is early access to the next version of Android although it won't have the functionality and user interface of the final product," Grey said.

The emulator on 32-bit platforms isn't as good as testing code on actual 64-bit ARM hardware, but it's better than nothing, Grey said.

Intel has already demonstrated a 64-bit version of Android 4.4, but for its x86 processors. Only a handful of smartphones and tablets use x86 processors, and the Intel build is a preview release of "pre-alpha quality," according to Intel's open-source website.